Manual mode indicates that changes are not automatically pushed or pulled.
Polling mode runs the sync loop without opening a watch stream.
Realtime mode indicates that changes are automatically pushed and pulled.
RealtimePushOnly mode indicates that only local changes are automatically pushed.
RealtimeSyncOff mode indicates that changes are not automatically pushed or pulled,
but the watch stream is kept active.
SyncModedefines synchronization modes for the PushPullChanges API (documents) and the RefreshChannel heartbeat (channels).